1. Field of the Invention
The invention relates to a pattern transfer method, especially, a pattern transfer method using an imprint lithography technology for transferring a micropattern.
2. Related Art
In a manufacturing process of semiconductor devices, a nano-imprint technology to transfer a shape of an original plate to a substrate to be transferred is attracted as a technology which can satisfy both formation of a micropattern and mass productivity. The nano-imprint technique is a technique where the shape of the original plate (template), on which a pattern to be transferred is formed, is pressed to a resist applied on the substrate to be transferred, and then the resist is cured, thereby transferring the pattern formed on the original plate to the resist.
The imprint lithography is divided into some types such as a light (UV) imprint and a heat imprint according to the imprint agent (curing way). The light imprint lithography has a step of coating the substrate to be processed with a light curing imprint agent, a step of aligning the substrate to be processed with the translucent template (alignment), a step of contacting the template with the light curing imprint agent, a step of curing the light curing imprint agent by light irradiation at this state, and a step of removing the template (template-removing) from the cured light curing imprint agent (resist pattern).
For example, Patent Document 1 (JP-A No. 2005-527974 (Kohyo)) discloses a technique to press a template to a substrate having a shape-formable surface by using a fluid induction pressure from an electric or magnetic field. More specifically, there has been proposed a technique where an assembly is arranged between conductive films and the electric field is applied between the films, and a technique where an assembly is arranged between films composed of magnetic materials and the magnetic field for combining the films is applied.
Furthermore, Patent Document 2 (JP-A No. 2004-311514 (Kokai)) discloses a technique to suppress degradation of a dimension controllability of a resist by neutralizing electric charges on the resist and a mold when the mold is in touch with the resist. More specifically, when the mold is in touch with the resist, the negative electric charge on the resist moves through a conductive film to the positive electric charge on the micropattern of the mold, thereby neutralizing the charges due to a static electricity on the mold and the resist.
However, the conventional imprint lithography has following problems. On the step of removing the template, because the resist has already been cured, a frictional force occurs between the pattern and the template depending on the contact area of the pattern and the template. That is, in a case of a pattern with a high aspect ratio, defects can occur, for example, the pattern is broken due to the frictional force or the like. Therefore, there have been problems that it is difficult to suppress the occurrence of the pattern defect on template-removing and to realize a high throughput of template-removing.